A mass spectrometric analysis of CF4/O2 plasmas: Effect of oxygen concentration and plasma power

A quadrupole mass analyzer was used to detect the neutral products extracted downstream from a CF4/O2 RF discharge at 80 mtorr. Stable discharge products are reported as a function of plasma power, residence time, oxygen concentration, and plasma voltage standing-wave ratio. In general, as plasma power increased from 10 to 200 W, production of CO increased while the measured mole fractions of CO2 and COF2 stabilized. The ratio of CO to CO2 decreased at low plasma powers as the oxygen concentration increased. An increase in the relative conversion of CF4 to oxygenated products occurred at both low plasma powers and low oxygen concentrations. Several mechanisms are suggested to account for these results.